Tension mechanism for band-saw mills.



PATENTED AUG. 30, 1904.

E. E. THMAS. TENSION MBGHANISM FOR BAND SAW MILLS.

APPLICATION FILED JAN. l1, 1904.

SHEETS-SHEET l.

N0 MODEL.

///J AUTOR/vf Y6 B. E. THOMAS.

TENSION MEGHANISM FOR BAND SAW MILLS.

APPLIGATION FILED JAN. 11. 1904.

PATBNTED AUG'. so, 1904.

No. 768,707. PATENTED AUG. 30, 1904.

E. E. THOMAS. TENSION MECHANISM FOR BAND SAW MILLS.

APPLICATION FILED JAN. 11, 1904.

N0 MODEL. 3 SHEETS-SHEET 3.

QL -uu- Urrrrian EDVIN E. THOMAS, F X/iCUiLi,

METTE IRON t PORA'HON.

TENSlGN' Patented .august so', 1904.

SPECFICATION forming part or" Letters atent No. 758,707, dated August30, 1904.-.

Application January ll, 19011. Serial lo. 188,423. (No model.) l

Be it known that I, EDWIN Teoras, of Tacoma, county of Pierce, State oflilashington, have invented certain new and useful lmprovements inTension Mechanisms for Band- Saw Mills, of which the following is aspeciiication. A

The object of my invention is to provide a band-saw tension or strainingdevice that is simple in construction, fully exposed to view,A andeasily accessible for the purpose of operation and repairs.

A further object is to provide a tension or strainingmechanism in whichthe use of gears, usually partially concealed, worms, and similardevices that are liable to become clogged with dirt and sawdust andrender the tension device less sensitive and interfere with thesuccessful operation of the mill is entirely avoided.

A further object is to provide a tension mechanism which can be easilyandquickly manipulated for the purpose of lowering the upper band-wheelto release the saw or raising the said wheel to tension the saw.

Other objects of the invention will appear from the following' detaileddescription.

lThe invention consists generally in various constructions andcombinations, all as hereinafter described, and particularly pointed outin the claims.

In the accompanying drawings, forming part of this specification, Figure1 is a front View of a. band-mill with my tension device appliedthereto. Fig. 2 is a side view of the same. Fig. 3 is an enlarged detailview of the tension mechanism. Fig. el is a section substantially on theline g/ e/ of Fig. 3.

In the drawings, 2 represents the base or bed of a band-mill, beneathwhich is the shaft 3 of the lower band-mill, mounted in bearingssupported by dependinghangers s. A driven pulley 5 is provided on saidshaft, and a belt 6 connects the said shaft with a mechanism foroperating the lumber-roll 7. VUpon the base or bed 2 l arrange standardsor brackets 8, whereon sleeves 9 are mounted. 10 repsents verticalcolumns that are slidable in said sleeves and have bearings 11 at theirupper ends for the shaft 12 of the upper bandwheel 13.

14 represents the saw,(shown in Fig. 2,) provided with a double cuttingedge; but l do not wish to confine myself to this construction, as a sawwith a single cutting edge may be provided, if preferred.

15 represents the upper guide for the saw and forms the subject-matterof acompanion application for Letters Patent of the United States liledherewith, and make no claim, therefore, in this application thereto, itbeing sufficient to say that it is pivotally mounted upon avertically-movable support 16, that is operated by means of asteam-cylinder 17 and an oscillating' bar 18, having Iits ends connectedto the piston of said cylinder and with said support.

'A rock-shaft19 is mounted on the upper ends of the brackets 8 and isprovided with oscillating arms 20, having curved lsurfaces that formbearings for chains 21, connected to said arms and to the bearings 11 ofthe upper band-wheel shaft. The oscillation of these arms serves toraise or lower the upper band-wheel and tension the saw or relieve thesame. A rock-shaft 22 is mounted in bearings on the brackets 8 below theupper band-wheel and is provided with arms 23, pivotally connected byrods 24: with the arms 20, and a quadrant-shaped arm 25 is secured onone end of the rock-shaft 22 and connected by a chain 26 with acounterbalance-frame 27, carrying a series of counterbalance-weights 28.This counter-balance mechanism for the upper band-wheel is substantiallythe same in construction and operation as that shown andl described inLetters Patent of the United States issued to me February 11, 1902, No.693,337, and l make no claim, broadly, to the same herein.

Loosely mounted at one end of the rockshaft 22 is a tension-arm 29, onthe outer end of which a tension-weight 30 is suspended. A bracket 31 isprovided on the bed of the mill and supports a lever 82, that is pivotednear one end thereon, and the long arm of the lever 32 extends vunderthe rock-shaft 22 and. is pivotally connected by a rod with theloosely-mounted tension-arm '29 near its inner end. A similar arm 34 ispivoted on the short arm of the lever 322 and carries a g'ripblock atits upper end. This block has a recess 36 in one side to receive the rim37 of a wheel 38, that is secured on the roch-shaft 22, and has itsspokes all arranged on one edge of the rim to allow the opposite edg'eto enter the recess 36. A movable gripping-jaw 39 is provided in thebleek 35, arranged to be eng'aged by the end of a screw l0, having anoperating-wheel 41, and moved into contact with the outer surface of therim 37. By means of this jaw and screw the grip-block can be securelylocked on the arm of the wheel and through the lever 32 and itsconnections the power of the tension-weight applied to the wheel andsaw. A hand-lever 42 is pivoted at one end on the bracket 3l and isprovided with a short arm 4?), pivotally connected with the arm 29 by alink 4A. When this hand-lever '-LQ .is tln'own down to a horizontalposition, as shown by dotted lines in Fig. 3, the loosely-mounted arm 29will be elevated, to and locked in the position shown by dotted lines insaid ligure and the lever 32 will be relieved of the tension-weight 230,and the grip block having been released from the wheel the latter may berevolved in either direction to raise or lower the counterbalanced upperband-wheel.

The operation of my improved tension device is as follows: Supposing themechanism is in the position indicated by Fig. l and it is desired toalter the tension of the saw or replace it with another', the operatorgrasping the lever 42 will swing it down to the position indicated bydotted lines in Fig. 3, elevating the arm 29 and its tension-weight totheir inoperative position and tilting the lever 32, the gripping devicehaving lirst been released from the wheel-rim. will now loe relieved ofthe tension-weight, and the operator grasping it (the wheel) can lowerthe upper band-wheel if it is desired to relieve the tension or take olfthe saw. After the saw has been removed and another put in place thereofin the usual way the operator will revolve the grip-wl'leel and with theaid of the counterbalance raise the upper bandwheel to its highestposition or until the saw is taut, then lock the grip-jaw securely tothe end of the wheel and raise the lever l2 to its upright position,when the force exerted by the weight 3() will again be applied to thelever and from thence transmitted through its connections to the gripblock and wheel and finally applied to the saw to tension the same.

l claim as my invention- 1. In a band-saw mill, the combination, withThe g'rip-wheel f the upper band-wheel and its shaft, of a rockshafthaving operative connections with said band-wheel shaft, a grip-wheelsecured on said rock-shaft, an arm loosely mounted on said rock-shaft, atension-weight carried by said arm, a grip-block having' a jaw arrangedto engage the rim of said wheel, means for operating said jaw, operativeconnections provided between said arm and said block, and means forraising and lowering said arm.

2. ln a band-saw mill, the combinatiomwith the upper band-wheel and itsshaft, of a rockshaft having operative connections with said band-wheeland shaft, a grip-wheel secured on said rock-shaft, an arm looselymounted on said rock-shaft, a tension-weight carried by said arm, agrip-block having' a jaw arranged to clamp said grip-wheel, a mechanismconnecting said arm and said grip-block for applying the tension-weightto said grip-wheel, and means for locking said arm and relieving saidgrip block and wheel of the strain of said weight thereon, substantiallyas described.

3. A tension device for band-saw mills,comprising' a rock-shaft havingoperative connections with the upper band-wheel shaft, a wheel securedon said rock-shaft, an arm loosely mounted on said shaft, a weightcarried by said arm, a grip-block having a jaw for engaging the rim ofsaid grip-wheel, a mechanism connecting' said arm and block fortransmitting the strain of said weight to said block and grip-wheel, anda mechanism within control of the operator for relieving the strain onsaid block and wheel, for the purpose specified.

LL. A tension device for band-saw mills, comprising' a rock-shaft, awheel secured thereon having its spokes connected to one edge of itsrim, an arm loosely mounted on said shaft, a grip-block having a recessto receive the opposite edge of said rim from said spokes, a movable jawprovided in said grip block, means for operating said jaw, atension-weight carried by said arm, a mechanism connecting said arm andsaid grip-block for transmitting to said block and wheel the power ofsaid weight, and means for raising and locking said. arm to relieve saidblock and wheel, substantially as described.

ln a tension device for band-saw mills, the combination, with arock-shaft, of a gripwheel secured thereon, a grip-block having a jaw toengage the rim of said wheel, a mechanism connected with said grip-blockand having a tension-weight for applying' a strain thereto and saidwheel, and means for temporarily relieving' the strain on said block andwheel, for the purpose specified.

6. ln a tension device for band-saw mills7 the combination, with arock-shaft, of a gripwheel secured thereon, a grip-block having' amovable jaw to engage said wheel, a looselymounted member having' aweight and operatively connected with said grip-block to apply thestrain of said weight thereto, and a lOO TIO

IZO

lever device within Control of the operator for relievingthe strain insaid bloel and wheel, substantially as described.

7. In a tension device for band-saw mills, the combination, with theupper band-wheel and its shaft, of a rock-shaft having' operativeconnections with said band-wheel shaft, a grip-wheel secured on saidrock-shaft, a eounterbalanee also mounted on said rock-shaft, anoscillating arm, a tension-weight Carried thereby, a movable jawarranged to grip the rim of said wheel, operative Connections providedvbetween said weighted arm and said jaw for transmitting the power ofsaid tension-weight to said jaw, and means for leeking said oscillatingarm to relieve said jaw of the weight thereon, substantially asdescribed.

8. In a tension device for band-saw mills, the Combination, with theupper band-wheel and its shaft, of a rock-shaft having operativeconnections' with said band-wheel shaft and provided with a suitableeounterbalaneemeehanism, a grip-wheel secured on said roekshaft, anoscillating' arm, a tension-weight carried thereby, a movable jawarranged to engage and grip the rim of said wheel, a lever mechanismconnecting said arm and said jaw, a pivoted operating-lever, and a linkconnecting said operating-lever and said Varm for raising the'latter torelieve said jaw of said weight, substantially as described..

In witness whereoil I have hereunto set my hand this Lith day ofJanuary, 1904.

EDVIN E. THOMAS.

